DL1/Notch1 signaling induces up-regulation of GATA-3 and down-regulation of Spi-B. RT-PCR analysis of HES-1, GATA-3, and Spi-B mRNA was performed on CD34⁺CD1a^- cells after 24 hours of coculture with OP9-DL1, OP9-Jag1, or control cell lines. Values were normalized to freshly isolated cells. The ribosomal protein p0 was used as internal control. The error bars represent SDs of triplicate samples. One representative experiment of 4 is shown.